Source: From a 1998 Hershey's Food Company Ad in the newspaper

1 1/2 cups (3 sticks) butter or margarine, melted
3 cups granulated sugar
1 tablespoon vanilla extract
5 eggs
2 cups all-purpose flour
1 cup HERSHEY'S Cocoa
1 teaspoon baking powder
1 teaspoon salt
24 small (1 1/2-inch) York Peppermint Patties

Preheat oven to 350 degrees F. Grease a 13 x 9-inch baking pan.

In large bowl with spoon or wire whisk, stir together butter, sugar and vanilla extract. Add eggs; stir until well blended. Stir in flour, cocoa, baking powder and salt; blend well. Reserve 2 cups batter; set aside.

Spread remaining batter in prepared pan.

Unwrap Peppermint Patties. Arrange patties in single layer over batter, about 1/2 inch apart. Spread reserved 2 cups batter over patties. Bake for 50 to 55 minutes or until brownies begin to pull apart from sides of pan. Cool completely in pan on wire rack, cut into squares.

Yield: about 36 brownies